Sympatric, temporally isolated populations of the pine white butterfly Neophasia menapia, are morphologically and genetically differentiated

Abstract

Temporal isolation remains an understudied, and potentially under-appreciated, mechanism of reproductive isolation. Phenological differences have been discovered in populations of the pine white butterfly (Neophasia menapia), a typically univoltine species found throughout western North America. At two locations in the Coast Range of California there are two periods of adult emergence per year, one in early summer (July) and one in late summer/autumn (September/October). Differences in flight time are accompanied by differences in wing shape and pigmentation. Here we use a combination of population genomics and morphological analyses to assess the extent to which temporal isolation is able to limit gene flow between sympatric early and late flights. Not only did we detect both genetic and morphological differences between early and late flights at the two sites, we also found that the patterns of differentiation between the two flights were different at each location, suggesting an independent origin for the two sympatric flights. Additionally, we found no evidence that these sympatric flights originated via colonization from any of the other sampled localities. We discuss several potential hypotheses about the origin of these temporally isolated sympatric flights.

Moths passing in the night: Phenological and genomic divergences within a forest pest complex

“…Temporal isolation of potentially interbreeding evolutionary lineages can be a significant contributor to species diversification (Hendry & Day, 2005; Nosil, 2012; Rundle & Nosil, 2005). Such phenological divergences may occur at different temporal scales, whether within a day (e.g., Devries et al, 2008; Schöfl et al, 2009; Ueno et al, 2006), seasonally (e.g., Adamski et al, 2018; Bell et al, 2017; Yamamoto & Sota, 2009), or between years (Cooley et al, 2003; Gradish et al, 2015). Multiple ecological and physiological processes may lead to temporal isolation, and it is almost always difficult to determine whether present‐day phenological divergence was the initial cause or a later reinforcing consequence of reproductive isolation (Egan et al, 2015; Taylor & Friesen, 2017).…”

Spatial and temporal patterns in the population genomics of the European cockchafer Melolontha melolontha in the Alpine region

“…Population differentiation based on different breeding and/or spawning time, regardless of spatial location, has been observed in several species, such as in the migratory fish Salminus brasiliensis (Ribolli et al, 2017 ) and the frog Rana arvalis (Richter‐Boix et al, 2013 ). Although still little studied, temporal population genomic structure has also been observed in insects with long life cycles or multiple emergence periods, such as the butterfly Neophasia menapia (Bell et al, 2017 ) and the moth Thaumetopoea pityocampa (Santos et al, 2011 ). In M. melolontha , the temporal synchronization of the life cycle allows reproduction between adults during swarming flights, whereas collections with a non‐synchronized life cycle would not reproduce due to incompatible developmental stages.…”

Phylogeography and population genetics of pine butterflies: Sky islands increase genetic divergence

“…We used the restriction enzymes EcoRI (NEB, R3101 20,000 units/ml) and MseI (NEB, R0525 10,000 units/ml). These two enzymes have been successfully used to obtain 20,737 SNPs in an independent population genomics study on N. menapia (Bell, ). Unique barcodes, ranging from 8 to 14 bases in length, and adaptors were then ligated to the EcoR1 ends of digestion fragments and common adaptors were ligated to the MseI termini.…”